Piston type internal combustion engines generally utilize mechanically driven camshafts and valve gear for operation of intake and exhaust valves. Electric and hydraulic valve actuators have also been proposed in order to provide improved control of valve actuation and timing.
A hydraulic valve system may comprise a hydraulic pump, a controller, a hydraulic fluid manifold, and one or more pistons reciprocable in a hydraulic cylinder provided in the hydraulic fluid manifold. The manifold delivers hydraulic fluid to the hydraulic cylinder to reciprocate the pistons and actuate an associated intake or exhaust valve. A position sensor may also be mounted to the manifold to feed back the valve position to the controller.
Mounting of the hydraulic cylinder and pistons and the position sensor in the manifold increases its complexity and complicates assembly, disassembly and serviceability of the assembly. Modification of the hydraulic components is also complicated by the expense of changes required in design and manufacture of the manifold. A more cost effective and serviceable hydraulic valve actuator for engine valves was desired.